Light emitting unit, apparatus and method for manufacturing the same, apparatus for molding lens thereof, and light emitting device package thereof

ABSTRACT

A light emitting unit, an apparatus and method for manufacturing the same, an apparatus for molding a lens thereof, and a light emitting device package thereof, which are capable of achieving an enhancement in light extraction efficiency and an improvement in mass productivity, are disclosed. The light emitting unit manufacturing apparatus includes a mold including a first mold and a second mold coupled to each other under a condition in which at least one light emitting unit is interposed between the first and second molds, a groove formed in one of the first and second molds at a position facing the light emitting unit, the groove having a lens shape, and a passage extending from an outer surface of the mold to the groove.

This application claims the benefit of Korean Patent Application No.10-2006-0052037, filed on Jun. 9, 2006, which is hereby incorporated byreference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light emitting unit, an apparatus andmethod for manufacturing the same, an apparatus for molding a lensthereof, and a light emitting device package thereof, and moreparticularly, to a light emitting unit, an apparatus and method formanufacturing the same, an apparatus for molding a lens thereof, and alight emitting device package thereof which are capable of achieving anenhancement in light extraction efficiency and an improvement in massproductivity.

2. Discussion of the Related Art

Generally, liquid crystal display (LCD) devices, which are a kind oflight reception type flat display, have no ability to emit light byitself. For this reason, such an LCD device forms an image byselectively transmitting illumination light irradiated from the externalof the LCD device. To this end, a light source must be arranged at theback side of the LCD device, in order to illuminate the LCD device. Thislight source is called a “backlight unit (BLU)”.

Such a backlight unit must uniformly irradiate light over the overallsurface of a liquid crystal panel. To this end, where light emittingdiodes (LEDs) are used for light emitters of the backlight unit, it isnecessary to arrange a lens on a package of each LED, in order to obtaina uniform brightness distribution of illumination light.

For an example of a method for installing a lens on an LED package,there is a method in which a lens is injection-molded using an epoxyresin or polycarbonate (PC)-based resin, and the molded lens is attachedto an LED package.

The attachment of the lens to the LED package may be achieved using amethod shown in FIG. 1. That is, as shown in FIG. 1, an encapsulatematerial 11 is filled in a region defined over an LED 12 of an LEDpackage 10, and a lens 20 is then attached to an upper surface of theLED package 10 filled with the encapsulate material 11.

In this case, for the encapsulate material 11 of the LED package 10, amaterial such as silicon is used. However, when the lens 20, which ismade of an epoxy resin or a PC-based material, is attached to theencapsulate material 11 which is a silicon, the following problems mayoccur.

First, when the lens 20 is made of an epoxy resin, it has no bondingforce to silicon, which is used for the encapsulate material 11. Forthis reason, an air layer is formed between the two materials.

When an air layer is formed between the two materials, as mentionedabove, light may be totally reflected while passing through the siliconencapsulate material 11 and the epoxy resin lens 20. As a result, a partof light emerging from the LED 12 cannot directly reach the lens 20.

Since the light travels along a complex path between the encapsulatematerial 11 and the lens 20 due to such a total reflection phenomenon,the number of light beams finally emerging out of the LED package 10 isreduced. As a result, a reduction in light amount occurs. For thisreason, practically, a degradation in brightness occurs.

Furthermore, when the epoxy resin used for the lens 20 is exposed to ahigh temperature condition for a prolonged period of time, a yellowingphenomenon may occur. For this reason, when the lens 20 may bediscolored in the manufacture thereof, so that it may function as a mainfactor of a degradation in light amount.

Second, when the lens 20 is injection-molded using a PC-based resin,interfaces are formed between the silicon encapsulate material 11 andthe PC lens 20, similarly to the former case. Due to a full reflectionphenomenon occurring at the interfaces, a degradation in the lightamount of the LED package 10 may occur.

Meanwhile, in the case of a modulized LED package, it is generallyformed using a reflow process. A temperature increase to about 270° C.may occur during the reflow process.

However, in association with the PC lens 20, there is a difficulty inexecuting the reflow process. This is because the material of the PClens 20 is a thermoplastic resin, so that the PC lens 20 may be deformedat a temperature of 160° C. or more due to melting thereof.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a light emitting unit,an apparatus and method for manufacturing the same, an apparatus formolding a lens thereof, and a light emitting device package thereof thatsubstantially obviate one or more problems due to limitations anddisadvantages of the related art.

An object of the present invention is to provide a light emitting unit,an apparatus and method for manufacturing the same, an apparatus formolding a lens thereof, and a light emitting device package thereofwhich are capable of basically solving formation of interfaces between alens and an encapsulate, and thus, achieving a maximum light extractionefficiency and an improvement in mass productivity.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, alight emitting unit manufacturing apparatus comprise: a mold including afirst mold and a second mold coupled to each other under a condition inwhich at least one light emitting unit is interposed between the firstand second molds; a groove formed in one of the first and second moldsat a position facing the light emitting unit, the groove having a lensshape; and a passage extending from an outer surface of the mold to thegroove.

In another aspect of the present invention, an apparatus for moldinglenses on light emitting units comprises: a mold including a first moldand a second mold coupled to each other under a condition in which thelight emitting units are interposed between the first and second molds;grooves formed in one of the first and second molds at positions facingthe light emitting units, respectively, each groove having a lens shape;a passage extending from an outer surface of the mold to the grooves;and an injection port connected to the passage.

In another aspect of the present invention, a light emitting devicepackage comprises: a package body on which a light emitting device ismounted; and a lens directly molded on the package body mounted with thelight emitting device, wherein there is no interface between the lensand the package body.

In another aspect of the present invention, a light emitting devicepackage comprises: a package body on which a light emitting device ismounted; a filler arranged on the package body; and a lens moldedintegrally with the filler.

In another aspect of the present invention, a method for manufacturing alight emitting unit comprises simultaneously molding a filler and a lenson the light emitting unit.

In still another aspect of the present invention, a method formanufacturing a light emitting device package comprises: mounting alight emitting device on a package body; and directly molding a lens onthe light emitting device mounted on the package body.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is an exploded perspective view illustrating a conventionalmethod used to attach a lens to a light emitting diode;

FIG. 2 is a sectional view illustrating a first embodiment of thepresent invention;

FIG. 3 is a sectional view illustrating another example of a lens-shapedgroove according to the present invention;

FIG. 4 is a plan view illustrating an example of a passage according tothe present invention;

FIG. 5 is a sectional view illustrating a second embodiment of thepresent invention;

FIG. 6 is a sectional view illustrating a third embodiment of thepresent invention;

FIG. 7 is a sectional view illustrating a modification of the thirdembodiment of the present invention; and

FIG. 8 is a flow chart for explaining a light emitting unitmanufacturing method according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

The present invention may, however, be embodied in many alternate formsand should not be construed as limited to the embodiments set forthherein. Accordingly, while the invention is susceptible to variousmodifications and alternative forms, specific embodiments thereof areshown by way of example in the drawings and will herein be described indetail. It should be understood, however, that there is no intent tolimit the invention to the particular forms disclosed, but on thecontrary, the invention is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the invention asdefined by the claims.

Like numbers refer to like elements throughout the description of thefigures. In the drawings, the thickness of layers and regions areexaggerated for clarity.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms.

These terms are only used to distinguish one region, layer or sectionfrom another region, layer or section. Thus, a first region, layer orsection discussed below could be termed a second region, layer orsection, and similarly, a second region, layer or section may be termeda first region, layer or section without departing from the teachings ofthe present invention.

First Embodiment

Referring to FIG. 2, a mold 100 according to a first embodiment of thepresent invention is illustrated. The mold 100 includes two partscoupled to each other while receiving light emitting units 200therebetween.

In detail, the mold 100 includes a first mold 110 and a second mold 120.Lens-shaped grooves 121 are formed in one of the first and second molds110 and 120 at positions corresponding to the light emitting units 200,respectively. A passage 122 is formed in the mold 100 such that thepassage 122 is connected to the grooves 121.

Each groove 121 is formed to have a shape correspond to an engravedshape of the lens to be formed on each light emitting unit 200.

The grooves 121 and passage 122 may be provided at any one of the firstand second molds 110 and 120. For simplicity of description, thefollowing description will be given in conjunction with the case inwhich the grooves 121 and passage 122 are provided at the second mold120.

The passage 122 connects the grooves 121 to the outside of the secondmold 120 formed with the passage 122. Preferably, an injection port 123is formed at an outer end of the passage 122.

The passage 122 includes a plurality of branch passages branched fromthe injection port 123 to respective grooves 121. Preferably, the branchpassages are identical in terms of a length extending from the injectionport 123 to each groove 121.

The injection port 123 may be formed at the second mold 120 where thepassage 122 is formed. The injection port 123 may have a diameter largerthan that of the passage 122. As shown in FIG. 2, the injection port 123may have a funnel shape.

The light emitting units 200 are arranged on the first mold 110 suchthat the lens-shaped grooves 121 are positioned on the light emittingunits 200, respectively, when the first and second molds 110 and 120 arecoupled to each other.

A plurality of light emitting units 200 may be arranged on the firstmold 110, as shown in FIG. 2. Accordingly, a plurality of lens-shapedgrooves may also be arranged.

Each light emitting unit 200 may be a light emitting diode (LED) packageincluding a lead frame. The light emitting units 200 may also be LEDsarranged on a printed circuit board (PCB).

Accordingly, a plurality of lenses can be simultaneously molded on theupper surfaces of the light emitting unit 200, respectively, by couplingthe first and second molds 110 and 120, and injecting a material forformation of the lenses into the injection port 123, thereby molding thelenses.

Meanwhile, various lens shapes may be applied to the lens-shaped grooves121 formed in the second mold 120, as shown in FIG. 3.

Using the second mold 120 which includes grooves 121 having differentlens shapes, as described above, it is possible to simultaneously moldlenses having different shapes. In this case, it is possible to obtainvarious light combinations, using lenses of various shapes.

As described above, the passage 122 may be formed such that the lengthsfrom the injection port 123 to respective grooves 121 are identical.Also, the passage 122 may be branched to group the grooves 121 or lightemitting units 200 into groups each including at least two grooves 121or light emitting units 200.

In this arrangement, there is an advantage in forming the passage 122such that the lengths from the injection port 123 to respective grooves121 are identical. The passage 122 may include first passages 122 a eachextending from the injection port 123 to an entrance of the associatedgroup where the associated grooves 121 are distributed, and secondpassages 122 b branched from each first passage 122 a, and respectivelyconnected to the grooves 121 of the group associated with the firstpassage 122 a.

A liquid material for molding of lenses flows along the passage 122after being injected into the injection port 123. In this case, theliquid material are injected from the injection port 123 into thegrooves 121 at the same pressure. If the lengths of the passage 122 fromthe injection portion 123 to respective grooves 121 are different fromeach other, it is difficult to achieve uniform injection of the liquidmaterial.

The first and second molds 110 and 120 are coupled to each other underthe condition in which the light emitting units 200 are interposedbetween the first and second molds 110 and 120. The injection port 123is then connected to an injection molding machine (not shown), in orderto fill the liquid material in a space between the first and secondmolds 110 and 120, namely, a space defined by the lens-shaped grooves121 and light emitting units 200.

The liquid material for molding of lenses is then injected into the mold100 by the injection molding machine. The injected liquid material isinjected into the space between the first mold 110 having the grooves121 and the second mold 120.

The injected liquid material for molding of lenses is then cured. Thus,lenses are molded on the light emitting units 200 in a bonded state,respectively.

Second Embodiment

Referring to FIG. 5, a mold 100 according to a second embodiment of thepresent invention is illustrated. The mold 100 includes a first mold 110and a second mold 120. Lens-shaped grooves 121 are formed in the firstmold 110 of the mold 100. A light emitting unit 200 is arranged on thesecond mold 120.

Passages 122 are formed in the second mold 120 such that the passage 122is connected to the grooves 111, as in the first embodiment. Aninjection port 123 is formed at an outer end of the passage 122.

The light emitting unit 200, which is attached to the second mold 120,may comprise a plurality of light emitting diodes (LEDs) or LEDpackages. In particular, for the light emitting unit 200, a plurality ofLED packages 220 mounted on a printed circuit board (PCB) 210 may beused.

Where the LED packages 220 mounted on the PCB 210 are arranged on thesecond mold 120, it is preferred that the PCB 210 be connected to thepassage 122.

The lens-shaped grooves 111 are arranged in the first mold 110 atpositions corresponding to the LED packages 220, respectively. Eachlens-shaped groove 111 is shaped to completely cover the associated LEDpackage 220.

The first and second molds 110 and 120 are coupled to each other underthe condition in which the light emitting unit 200 is interposed betweenthe first and second molds 110 and 120. The injection port 123 is thenconnected to an injection molding machine (not shown), in order to filla liquid material for molding of lenses in a space between the first andsecond molds 110 and 120, namely, a space defined by the lens-shapedgrooves 121 and light emitting unit 200.

The liquid material for molding of lenses is then injected into thepassage 122 of the mold 100 by the injection molding machine. Theinjected liquid material is injected into the space between the firstmold 110 having the grooves 111 and the second mold 120.

The injected liquid material for molding of lenses is then cured. Thus,lenses are molded on the light emitting unit 200 in a bonded state.

The remaining configurations in this embodiment are identical to that ofthe first embodiment, so that no description thereof will be given.

Third Embodiment

Where the LED packages 220 mounted on the PCB 210 are used for the lightemitting unit 200, leads are printed on the PCB 210 to configure adesired circuit.

In this case, when the first and second molds 110 and 120 are coupled toeach other, a pressure of several tons is applied to the leads printedon the PCB 210. As a result, the leads may be damaged.

In order to prevent the leads of the PCB 210 from being damaged due tothe coupling pressure between the first and second molds 110 and 120,PCB protectors 230 or 231, which are made of a material having anelasticity, may be provided at contact portions of the mold or PCB 210,as shown in FIG. 6 or 7.

As shown in FIG. 6, each PCB protector 230 may be arranged around theassociated lens-shaped groove 111 while having the same shape as thelens-shaped groove 111. In particular, each PCB protector 230 may beformed in the form of a strip extending along the periphery of theassociated lens-shaped groove 111.

Alternatively, PCB protectors 231 may be formed on the PCB 210, as shownin FIG. 7. The PCB protectors 231 formed on the PCB 210 function toalleviate the pressure applied between the PCB 210 and the first mold110 when the first and second molds 110 and 120 are coupled to eachother.

Meanwhile, the PCB protectors 231 may have the form of circularprotrusions having a height larger than that of the leads on the PCB210.

Hereinafter, a method for manufacturing light emitting units includinglenses, using a light emitting unit manufacturing apparatus according tothe present invention, will be described. The following description willbe given in conjunction with the case in which a single light emittingunit 200 including a plurality of lenses is manufactured.

As shown in FIG. 8, the light emitting unit 200 is first arrangedbetween the first mold 110 and the second mold 120 such that the LEDs orLED packages of the light emitting unit 200 are aligned with the grooves111 or 121. In this state, the first and second molds 110 and 120 arecoupled to each other (S1).

Thereafter, the first and second molds 110 and 120 are heated toincrease the temperatures of the first and second molds 110 and 120(S2). The reason why the temperatures of the first and second molds 110and 120 should be increased is to prevent the lens-molding liquidmaterial injected through the injection port 123 from being cured duringflowing of the liquid material through the passage 122.

The lens-molding liquid material is then injected into the lens-shapedgrooves 111 or 121 (S3). In this case, the injection of the lens-moldingliquid material can be uniformly achieved because the lengths of thepassage 12 from the injection port 123 to respective grooves 111 or 121are identical, as described above.

As described above, it is preferred that the lens-molding liquidmaterial injected through the injection port 123 be an epoxy resin or asilicon resin. This is because the epoxy resin and silicon resin arethermosetting materials, so that they are not deformed even at a hightemperature of the mold 100.

Subsequently, the liquid material injected into the lens-shaped grooves111 or 121 through the injection port 123 and passage 122 is cured (S4).

Finally, the first and second molds 110 and 120 are separated from eachother. Thus, a direct molding process is completed. In accordance withthe direct molding process, a light emitting unit 200 integrally formedwith lenses can be manufactured.

In the light emitting unit 200 manufactured in the above-describedmanner, there is no interface between the PCB, on which LED packages orLEDs are mounted, to constitute the light emitting unit 200, and eachlens, because the lenses are integrally formed on the light emittingunit 200.

That is, no adhesive coating process is required for bonding of lensesto the light emitting unit 200. Accordingly, there is no interface, forexample an adhesive interface, between the light emitting unit 200 andeach lens.

The lenses molded in accordance with the above-described direct moldingprocess may function as fillers on the light emitting unit 200. In thiscase, the fillers and lenses may be considered as being simultaneouslyformed using a material such as an epoxy resin or a silicon resin.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A light emitting unit manufacturing apparatus comprising: a moldincluding a first mold and a second mold coupled to each other under acondition in which at least one light emitting unit is interposedbetween the first and second molds; a groove formed in one of the firstand second molds at a position facing the light emitting unit, thegroove having a lens shape; and a passage extending from an outersurface of the mold to the groove.
 2. The light emitting unitmanufacturing apparatus according to claim 1, wherein the at least onelight emitting unit comprises a plurality of light emitting units, andthe groove comprises a plurality of grooves.
 3. The light emitting unitmanufacturing apparatus according to claim 2, wherein the grooves havedifferent shapes, respectively.
 4. The light emitting unit manufacturingapparatus according to claim 2, wherein the plurality of light emittingunits and the plurality of grooves are grouped into groups eachincluding at least two of the light emitting units and at least two ofthe grooves.
 5. The light emitting unit manufacturing apparatusaccording to claim 1, wherein the light emitting unit comprises at leastone light emitting diode package.
 6. The light emitting unitmanufacturing apparatus according to claim 5, wherein the light emittingdiode package is mounted on a printed circuit board.
 7. The lightemitting unit manufacturing apparatus according to claim 1, furthercomprising: an injection port formed at the outer surface of the moldconnected to the passage.
 8. The light emitting unit manufacturingapparatus according to claim 7, wherein the groove comprises a pluralityof grooves, and the passage is branched into branch passagesrespectively extending from the injection port to the grooves.
 9. Thelight emitting unit manufacturing apparatus according to claim 7,wherein the lengths of the branch passages respectively extending fromthe injection port to the grooves are substantially same.
 10. The lightemitting unit manufacturing apparatus according to claim 1, wherein thegroove and the passage are formed in the first mold.
 11. The lightemitting unit manufacturing apparatus according to claim 1, wherein thegroove is formed in the first mold, and the passage is formed in thesecond mold.
 12. The light emitting unit manufacturing apparatusaccording to claim 1, further comprising: a board protector arranged ina region where the light emitting unit comes into contact with the firstmold or the second mold.
 13. The light emitting unit manufacturingapparatus according to claim 12, wherein the board protector is made ofan elastic material.
 14. The light emitting unit manufacturing apparatusaccording to claim 12, wherein the board protector is formed around thelens-shaped groove.
 15. The light emitting unit manufacturing apparatusaccording to claim 12, wherein the board protector is formed at thelight emitting unit.
 16. An apparatus for molding lenses on lightemitting units, comprising: a mold including a first mold and a secondmold coupled to each other under a condition in which the light emittingunits are interposed between the first and second molds; grooves formedin one of the first and second molds at positions facing the lightemitting units, respectively, each groove having a lens shape; a passageextending from an outer surface of the mold to the grooves; and aninjection port connected to the passage.
 17. The apparatus according toclaim 16, wherein the light emitting units and the grooves are groupedinto groups each including at least two of the light emitting units andat least two of the grooves.
 18. The apparatus according to claim 17,wherein the passage comprises: first passages each extending from theinjection port to an entrance of an associated one of the groups wherethe grooves of the associated group are distributed; and second passagesbranched from each first passage, and respectively connected to thegrooves of the group associated with the first passage.
 19. A lightemitting device package comprising: a package body on which a lightemitting device is mounted; and a lens directly molded on the packagebody mounted with the light emitting device, wherein there is nointerface between the lens and the package body.
 20. The light emittingdevice package according to claim 19, wherein the package body comprisesa plurality of aligned package bodies.
 21. A light emitting devicepackage comprising: a package body on which a light emitting device ismounted; a filler arranged on the package body; and a lens moldedintegrally with the filler.
 22. The light emitting device packageaccording to claim 21, wherein the filler and the lens are made of asilicon or epoxy-based material.
 23. A method for manufacturing a lightemitting unit, comprising: simultaneously molding a filler and a lens onthe light emitting unit.